1. Field of the Invention
The present invention relates in general to a video equipment such as a video cassette tape (VCR), a camcorder and the like, and more particularly to an apparatus and a method for loading a cassette tape in a video equipment.
2. Description of the Prior Art
Conventionally, in a video equipment, a direct current (DC) motor is provided for the purpose of executing of an unloading operation of mounting a cassette tape into a cassette mechanism of the video equipment and a loading operation of bringing the unloaded cassette tape into contact with a head of the video equipment for recording and playback of a video signal.
The DC motor generally has two terminals for application of a drive voltage thereto and rotates in normal or reverse direction according to the alternation in polarities of the applied drive voltage. These rotations of the DC motor cause the loaded or unloaded cassette tape to be unloaded or loaded, respectively.
Referring to FIG. 1, a block diagram of a conventional apparatus is shown for loading a cassette tape in a video equipment. As shown in this figure, the conventional cassette tape loading apparatus comprises a DC motor 1, a microcomputer 2 for controlling the video equipment, a driver 3 for controlling a drive voltage to be applied to the DC motor 1 under the control of the microcomputer 2, and a switch 4 for detecting a mechanical rotation angle of the DC motor 1 to detect an actuated state of the DC motor 1 such as, for example, load completion, unload completion, eject, stop and etc.
The operation of the conventional cassette tape loading apparatus with the above-mentioned construction will hereinafter be described.
The microcomputer 2 recognizes the current state of the DC motor 1 through the switch 4 and, in response to an instruction from the user, outputs a control signal to the driver 3 to load or unload the cassette tape. In response to the control signal from the microcomputer 2, the driver 3 controls the drive voltage to be applied to the DC motor 1. As a result, the DC motor 1 may rotate in normal or reverse direction and, furthermore, the cassette tape may be loaded or unloaded.
Amount of load which is applied to the DC motor 1 in loading the cassette tape can be represented by a graph in FIG. 2. As seen from this figure, the load amount which is applied to the DC motor 1 in the operation of loading the cassette tape is severe in variation.
However, the conventional cassette tape loading apparatus has the following disadvantages.
Since the drive voltage applied to the DC motor 1 through the driver 3 is constant in level until completion of the loading operation as shown in FIG. 3, the DC motor 1 rotates at a constant speed until completion of the loading operation. For this reason, in a case where the cassette tape is tightly wound, the rotation of the DC motor 1 is made at a relatively fast speed, resulting in a severe pull at the cassette tape. This severe pull at the cassette tape damages the cassette tape such as by stretching the tape. On the other hand, in a case where the cassette tape is loosely wound, the rotation of the DC motor 1 is made at a relatively slow speed, resulting in the cassette tape being tangled. As a result, when the video equipment is used for a long time, the life of the DC motor and the cassette mechanism in the video equipment may be shortened as well as causing damage to the cassette tape. Also, since the DC motor is subject to an overload, power consumption may be wasted. Further, the rotation of the DC motor cannot be smooth due to such wound states. This causes noise in the DC motor.